Oxygen-separating process.



No. 788,045. PATENTED FEB. 21, 1905. J. E. JOHNSON, JR. OXYGEN SEPARATING PROCESS.

APPLICATION FILED APR. so, 1903. I 2 SHEETS-SHEET 1.

WITNESSES:

6mm W M 0% y Wm A. M

OXYGEN SEPARATING PROCESS.

APPLICATION FILED APR. 30, 1903'.

2 SHEETS-SHEET 2.

a 2%? b g Patented. February 21, 1905v PATENT OFFICE.

JOSEPH E. JOHNSON, JR, OF LONGDALE, VIRGINIA.

OXYGEN-SEPARATING PROCESS.

SPECIFICATION forming part of Letters Patent No. 783,045, dated February 21, 1905. Application filed April 30,1903. Serial No. 15%945.

To (I/ZZ whom, it may concern.-

Be it known that I, J osnrn E. JOHNSON, J r., a citizen of the United States, and a resident ofLongdale, in the county of Alleghany and State of Virginia, have invented certain new 1 and useful Improvements in Oxygen-Separating Processes, of which the following is a specification.

My invention relates to a process of separating from the air the oxygen and nitrogen of which it is mainly composed; and its novelty consists in the several successive steps of the operation and in the means whereby they are carried out.

The object of my invention is to use ordinary air compressed and cooled and dried as the basis of the operation to be described.

It is well known that when liquid air is evaporated or passes from the liquid to the gaseous state a partial separation of the two gases of which it is composed may be made because the nitrogen boils at alower temperature than the oxygen when both are under the same pressure, and during evaporation the vapor which passes off first is nearly pure nitrogen and that which passes off last is nearly pure oxygen. It is also a fact that at the pressure of the atmosphere the specific gravity of liquid nitrogen is about 0.8, while that of liquid oxygen is 1.1.' This latter fact cannot readily be taken advantage of, however, as a means for separating the two elements, because liquid nitrogen and oxygen dissolve each other in all proportions to form a homogeneous solution similar to that formed by a mixture of alcohol and water. However, when in addition to the different specific gravities of the two elements advantage is taken of their different boiling-points a method of separation is possible; and the object of my invention is to utilize these differences for such purpose. I use the heat absorbed by the conversion of the separated gases from the liquid to the gaseous state and by the raising of their temperatures as nearly as possible to that of the atmosphere to bring about the liquefaction of the compressed air introduced to the apparatus, so that advantage may subsequently be taken of the difference in the specific gravities and boiling-points of the gases.

I employ a centrifugal separator for the purpose of utilizing this difference in specific gravities after partial evaporation has developed it.

In the drawings, Figure 1 is a vertical section and partial side elevation of the apparatus designed to carry out the successive steps of my process. Fig. 2 is an enlarged cross-section of the exchanger-pipe. Fig. 3 is an enlarged detail of the wall of the casing, showing the layers of insulating material. Fig. 4 is a horizontal transverse section of the turbine, and Fig. 5 is a side elevation of one of the turbine cups or buckets.

1n the drawings, B is a hollow shaft vertically placed. Near its bottom it is provided with a connection A, leading from the exchanger 1, presently to be described. At any suitable point there is arranged a ball-bearing R around this shaft, and above this ball bearing there is supported a turbine-case T, within which is a turbine of common form. Secured to the case T and arranged above it is a long pipe or sleeve-gland Z, terminating at its upper end in the centrifugal separatorcasing M. There is an enlargement of the pipe Z at S above the case T, and this communicates with a lateral pipe U, leading to the case. Within the pipe or sleeve-gland Z is a second hollow shaft Q, surroumling and concentric with the shaft B, to which it is rigidly secured in such a manner as to leave an annular space 2 between them-for instance, by inserting the pins (I to keep them apart. This shaft Q terminates at the enlargement S of the pipe Z, which between this point and the turbine-case T is a close running fit on the hollow shaft. In a similar manner the pipe Z closely fits the shaft Q above this point. The shaft Q terminates within the separator.

It may be said here that the nitrogen developed within the centrifugal separator C escapes into the annular space 2 between the shafts to the enlargement S and thence to the turbine t through the pipe U.

The rotation 9 able cover an and bottom on. casingis the centrifugal separator proper. consists of a conical shell L, provided with outlet-ports l. Within the shell L is a perforated diaphragm K, terminating in the upper and lower walls ofthe shell. \Vithin the diaphragm K are arranged three coils of pipes-an outer series of coils D, an intermediate series of coils E, and an inner series of coils F. The lowermost coils of the series D and E and the uppermost coils of the series E and F communicate with each other. The lowermost coil of the series F terminates in an upwardlyextending outlet-pipe G. The uppermost pipe of the series D communicates directly with the hollow shaft B, previously referred to, through the lateral pipe 7).

Surrounding the centrifugal separator-easing and the shafts and turbine-case is arranged the exchanger 1, above referred to. This consists of a long coiled pipe I, within which are four smaller pipes 0 11 12 a, with a space surrounding them and inside of the larger pipe. The four small pipes branch out at the top of the exchanger and lead to any suitable reservoirs for the oxygen and nitrogen discharged therefrom. The exchanger at its bottom communicates with the inner shaft B by the couplingA, above referred to. One of the smaller pipes, 0, of the exchanger is connected with the outer fixed shell M of the centrifugal separator by a small pipe 0, (the purpose of which will presently be referred to,) provided with a suitable control-valve 6, and the other three small pipes, 11 w a, of the exchanger are connected by a coupling Y to a pipe N, leading down from the turbine-case. The whole is surrounded by an external casing X, made of any suitable size and material and suitably insulated from the outer atmosphere by layers rr 0' of wool felt, mineral wool, or the like and provided with interior brackets 3 for the support of the exchanger. insulating-pieces 4 being inserted between the brackets and the exterior of the exchanger.

The turbine 23 is of usual form. It is provided with cu )s or buckets t and the )i 76UiS )ro l 1 l l l vided with a suitable nozzle 5, adapted to direct the stream of fluid against the buckets to cause the rotation of the turbine.

The operation of my device is as follows: Compressed air which has been cooled, freed from water-vapor, carbonic acid, and dust is introduced into the pipe I of the exchanger 1 at its top and within the space outside of the four small pipes 0 w. '21 71.. Passing down through the coils of the exchanger it becomes colder and colder from the fact that the nitrogen and oxygen produced in the apparatus are at the same time passing upward through the smaller pipes within the exchanger, the oxygen through the pipe 0 and the nitrogen through the three pipes '11 a n. In this manner the heat remaining in the cooled and compressed air is further removed to raise the ithin this 1 temperature of the outflowing oxygen and nitrogen, so that the incoming air by the time it reaches the bottom of the exchanger is cooled down to within a few degrees of the temperature of the discharging gases just subsequent to their evaporation from the liquid condition. From the exchanger 1 the air.is led inward toward the center of the coil through the connection A and enters the hollow shaft B. The air passes on up through the hollow shaft to its top, where it terminatesin the branch pipe 5, leading to the first or outermost series of coils D in the centrifugal separator. 1t passes downward through these coils until it reaches the lowermost one of the series, whence it passes into the coils E. It passes upward through the coils E until it reaches the uppermost one of that series, whence it passes into the coils F. It passes downward through this series of coils until it is permitted to escape through the outlet Gr, the terminal of the lowermost coil of this series. The coils are secured to and supported on the perforated diaphragm K, between which and the shell L of the centrifugal separator there is considerable annular space. All of these parts of the centrifugal separator rapidly revolve when the apparatus is in operation. It is well-known that when a body of liquid is rapidly revolved on a vertical axis its surface assumes the shape of a paraboloid of revolution, and the series of coils D, E, and F are so arranged as to conform roughly to the outline of such paraboloids. Assuming for the moment that the air within the interior of the centrifugal separator has been liquefied or that normal liquid air has been introduced therein, this liquid will be at a lower pressure and temperature than the air in the coils D, E, and F. Consequently as the air passes down through these coils it loses heat through the walls of the coil and is completely liquefied by the time it reaches the discharge-port G. This newly liquefied air is discharged into the body of liquid within the centrifugal separator. It at once begins to evaporate. The vapor which rises from it is almost wholly nitrogen, because of the fact that the nitrogen boils at a lower temperature than the oxygen and both are under the same pressure. The residual liquid, therefore, is largely oxygen. As soon as a large portion of the nitrogen has evaporated from the top or inner surface of the liquid the liquid remaining becomes much heavier than normal liquid air, owing to the greater specific gravity of liquid oxygen. in the meantime the nitrogen has escaped into the annular space 2 and caused the rotation of the turbine and of the centrifugal separator in the manner presently to be described. Under the influence of the centrifugal force set up by the high speed at which the centrifugal separator is rotated this layer of oxygen-laden liquid air which has ICC been deprived of part of its nitrogen sinks to the outermost space of the centrifugal separator, passing through the perforations of the diaphragm K. The liquid which is thus caused to move to the outer surface of the centrifugal separator is also moved away from the series of condensing-coils which constitute the source of heat which is causing the evaporation of the nitrogen. The process continuing, it is obvious that new layers of liquid air which have been deprived of a portion of their nitrogen are continuously formed, and as the process is kept up a body of pure, or almost pure, oxygen will be found at the outermost part of the apparatus, while the interior surface will consist of the liquid which has lastentered and which contains almost the quantity of nitrogen in the normal air. The outlet-ports Z of the conical shell L are located at or near its top, and therefore farthest away from the center of the inverted truncated cone. The outermost layers of the liquid are almost or quite pure oxygen and are permitted to How through these ports into the an-.

nular space between the shell L and the outer casing M. From this space it flows through the pipe (and the valve 6 being opened) down to the small pipe 0 of the exchanger, entering the exchanger in the case illustrated at the fourth coil from the bottom. It is desirable to have this counter-current coil for the oxygen enter at this place rather than at the extreme bottom of the apparatus, because the liquid oxygen is warmer than the escaping nitrogen, and it enters the exchanger, therefore, at a point where the cooled air coming down the exchanger is about at the same temperature as its own. The oxygen gradually passes up through the small pipe 0 of the exchanger 1, being converted from the liquid into the gaseous state as it progresses and is discharged at the top or conveyed into any suitable reservoir, as may be desired. The space within the centrifugal separator and above the surface of the liquid air is filled with practically pure nitrogen-vapor. This vapor passes into the top of the pipe Q, and so on down the annular space 2 to the outlet S, whence it passes through the pipe U to the turbine T, the peripheral speed of the turbine being such as to remove the energy of the nitrogen discharging against it as fully as possible. This turbine is the source of'rotation of the centrifugal separator. The nitrogen, having performed this work, leaves the turbine-case at the bottom and passes through the pipe N and coupling Y into the three small pipes 12, 02, and 71 ofthe exchanger 1, whence it flows upward alongside of the oxygen until it reaches the terminals of this series of pipes, whence it may be led into a reservoir and disposed of at will.

WVhile I have described my invention as relating only to the separation of oxygen and nitrogen from the air, it will of course be understood that it is readily applicable to the separation from a liquid of any of its ingredients having slightly-different boiling-points and specific gravities. For instance, it might be used in the separation of crude oils or of mixtures of alcohol and water.

The apparatus described in connection with the different steps of the process is by a requirement of the Patent Office eliminated from this case and made the subject of a separate application for Letters Patent.

hat I claim as new is 1. The process of separating substances having different boiling-points from a liquid, which consists in heating a body of the liquid to the boiling-point of the more volatile substance, withdrawing the gaseous product, and simultaneously rotating the body at a sufiicient speed to centrifugally separate the body into an inner evaporating portion and an outer portion of the residual liquid, as set forth.

2. The process of separating substances having different boiling-points from a liquid, which consists in heating a body of the liquid to the boiling-point of the more volatile substance, withdrawing the gaseous product, simultaneously rotating the body at a sufficient speed to centrifugally separate the body into an inner evaporating portion and an outer portion of the residual liquid, and withdrawing the separated liquid from the outer surface of the rotating body, as set forth.

3. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, and simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, as set forth.

4:. The process of separating nitrogen and oxygen from liquidair, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body,

thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, and withdrawing the liquid oxygen from the outer surface of the rotating body, as set forth.

5. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, expanding the evaporated nitrogen, and utilizing its expansion energy to effect rotation of said body, as set forth.

6. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby eentrifugally removing from the source of heat, the residual liquid rich in oxygen, and cooling another portion of air by the escaping nitrogen, as set forth.

7. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, sil'nultaneously rotating said body, thereby ccntrifugally removing from the source of heat, the residual liquid rich in oxygen, expanding the evaporated nitrogen, utilizing its expansion energy to effect rotation of said body, and cooling another portion of air by the escaping nitrogen, as set forth.

8. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centri'fugally removing from the source of heat, the residual liquid rich in oxygen,withdrawing and evaporating the liquid oxygen, and utilizing it to cool another portion of air, as set forth.

9. The process of separatingnitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, withdrawing the liquid oxygen from the outer surface of the rotating body, and employing the separated nitrogen and oxygen to cool another portiolf of air, as set forth.

10. The process of separatingnitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich inoxygen, expanding the evaporated nitrogen, utilizing its expansion energy to effect rotation of said body, and employing the separated nitrogen and oxygen to cool another portion of air, as

set forth.

11. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, cooling another portion of air by the escaping nitrogen, and liquefying the cooled air by transferring heat therefrom to the rotating body of liquid air, as set forth.

12. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, cooling another portion of air, and rotating the cooled air in proximity to the rotating body of liquid air, thereby compressing, cooling and liquefyil'ig it, as set forth.

13. The process of separating nitrogen and oxygen from liquid air, which consists in heating a body of liquid air to the boiling-point of nitrogen, withdrawing the evaporated nitrogen, simultaneously rotating said body, thereby centrifugally removing from the source of heat, the residual liquid rich in oxygen, cooling another portion of air, and rotating the cooled air in proximity to the rotating body of liquid air, thereby compressing, cooling and liqucfying it, as set forth.

itness my hand, this 21st day of April, 1903, at Longdale, in the county of Alleghany and State of Virginia.

JOSEPH E. JOHNSON, JR.

\Vitnesses:

S. R. ROBINSON, W. Al. O. J ONES. 

